The objective of this collaborative clinical research effort is to improve the care of patients with bladder carcinoma through studies of different aspects of clinical management. The studies are carried out in several institutions simultaneously according to well-designed protocols. A central laboratory is responsible for the uniform collection, classification and analysis of pathologic and cytologic material and all data are being collected, organized and analyzed in a central statistical office. In each participating institution the following protocols are being studied: Assessment and characterization of patients, their neoplasms and the fields from which the neoplasms arise; studies of systemic chemotherapy in patients with metastatic bladder carcinoma; studies of chemical intervention (prevention of recurrence) in patients with completely resected low-stage bladder lesions; and studies of systemic chemotherapy as adjuvant to definitive therapy of invasive bladder carcinoma. This application covers the proposed activities of the Central Pathology Laboratory.